Usually, the chambers are part of a tempering column in which the chambers are arranged above one another. Mass chambers through which the mass to be tempered flows are arranged between the chambers through which the tempering medium flows.
The present invention is especially applicable to the region of one or more cooling chambers through which a cooling medium flows. On the other hand, the present invention may be also used in any other portion of a tempering column, for example in a crystallization zone or a heating zone. Each chamber forms a disc-like hollow body being designed to be closed except an entrance and an exit being connected to a tempering circuit. The chambers include separating walls defining a flowing path, a canal or a channel for the tempering medium.
An apparatus for continuously tempering chocolate masses and the like is known from European Patent No. 0645222 B1. The apparatus includes a plurality of chambers, a tempering medium or a cooling medium flowing through some of these chambers. A mass chamber through which the mass to be tempered is pumped by means of a pump is arranged between two adjacent chambers through which the tempering medium flows. The chamber through which the tempering medium flows includes a plurality of separating walls. The separating walls are either arranged concentrically about the axis of the chamber, or they are arranged radially to the axis of the chamber. The axis of the chamber corresponds to the axis of the tempering column. The chamber further includes an entrance and an exit for the tempering medium. Shortly after the tempering medium enters the chamber through the entrance, there is a first turning point in which the flowing direction of the tempering medium is changed about 180.degree.. A second turning point follows after about 270.degree.. This second turning point also changes the flowing direction about 180.degree.. The tempering medium then flows back clockwise about 270.degree., and it reaches a third turning point. The second and third turning points already have the consequence of the tempering medium flowing in a radial outside direction. After the third turning point, the tempering medium keeps on flowing in a counter clockwise direction, until it reaches the fourth turning point, it changes its direction about 180.degree., and it flows in a radial outside direction and further on in a clockwise direction until it exits the chamber through the exit. Consequently, the chamber includes four turning points in which the direction of the tempering medium is changed by 180.degree.. Each of these turning points has the negative effect of a loss of pressure of the tempering medium. Thus, the pump pumping the tempering medium through the chamber has to supply extra pressure. Additionally, the flowing surface substantially changes in the region of the four turning points. It is well known that a change of the flowing surface results in a change of the velocity of the tempering medium at that point, so that changes of the heat being transferred occur. In case of the chamber being a cooling chamber which is connected to a cooling circuit, there will be zones, especially in the region of the turning points and in the region of the entrance and the exits, in which the tempering medium flows at a very low speed. Thus, the temperature of the tempering medium in these regions increases with respect to other regions in which the tempering medium flows at a higher speed. Especially in the precrystallization procedure of chocolate masses in a cooling or crystallization zone, it is desired to keep the temperature of the cooling surfaces within a small range. In case the temperature is too high, no crystals are formed in this region.
Additionally, different temperatures of the cooling surfaces occur in different regions of the chamber. In case of the tempering medium being a cooling medium, the tempering medium has the lowest temperature at the entrance of the chamber. The temperature of the tempering medium increases along the flowing path, so that it reaches its highest temperature at the exit of the chamber. Due to the arrangement of the separating walls of the known chamber, the lowest temperature of the cooling surface is realized in a circle-like region in a radial inside portion of the chamber. Radial outside portions of the chamber have a higher temperature of the cooling surface since this is the region in which the tempering medium returns toward the exit. Consequently, the cooling surfaces facing the mass to be tempered are cooler at a small radius than in the outward portion of the chamber. Thus, the cooling surfaces do not have the same temperature in all regions of the surface of the chamber.
It is known from German Patent No. 40 27 429 C2 that optimum crystals are formed in tempering machines when the temperature of the cooling surfaces facing the mass is kept constant. This means to keep the temperature constant at all locations of the surface of the chamber.